Methods of manufacturing a camera system having multiple image sensors

ABSTRACT

A method of manufacturing an image sensor from two defective image sensor arrays having identical structural design, each having substantially the same field of view and aligned to view substantially the same scene. The method includes providing a first defective image sensor array, having known defective pixels, providing a second defective image sensor array, having known defective pixels, and fusing the first image sensor array and the second image sensor array into a single output image array.

RELATED APPLICATION

The present application claims the benefit of U.S. provisionalapplication 61/167,226 filed on Apr. 7, 2009, the disclosure of which isincorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to imaging systems, and more particularly,the present invention relates to a method of manufacturing an imagingsystem from two or more image sensors having defective pixels.

BACKGROUND OF THE INVENTION AND PRIOR ART

In the production of image sensors, often, one or more pixels of theproduced image sensor are defective. The image sensor arrays are scannedand all detected defective pixels are sorted out, mapped and marked. Insome types of image sensors such a defective image sensor is rejected.In other types of image sensors such a defective image sensor iscomputed from the adjacently surrounding pixels, for example, from the 4or 8 adjacently surrounding pixels.

For Example, the yield of infra red (IR) image sensors is very low—about0.1-5%, due to defective pixels. Therefore, there is a need for and itwould be advantageous to have a method to substantially raise theproduction yield of image sensors, such as infra red image sensors.

SUMMARY OF THE INVENTION

According to teachings of the present invention, there is provided amethod of manufacturing an image sensor from two defective image sensorarrays having identical structural design, each having substantially thesame field of view (FOV) and aligned to view substantially the samescene. The method includes providing a first defective image sensorarray, having known defective pixels, providing a second defective imagesensor array, having known defective pixels, and fusing the first imagesensor array and the second image sensor array into a single outputimage array.

For each of the defective pixels of the first image sensor array therespective pixel from the second image sensor array is selected to be anoutput pixel of the output image array. For each of the defective pixelsof the second image sensor array the respective pixel from the firstimage sensor array is selected to be an output pixel of the output imagearray. For each valid pixel in the first image sensor array, having arespective valid pixel in the second image sensor array, either of therespective valid pixels is selected to be an output pixel of the outputimage array.

Preferably, the first defective image sensor array and the seconddefective image sensor array have no overlapping defective pixels.

In variations of the present invention, if the first defective imagesensor array and the second defective image sensor array haveoverlapping defective pixels, then for each of the overlapping defectivepixels, setting the value of a corresponding final output pixel in theoutput image array to be the average of the K immediately adjacentneighboring pixels of the overlapping defective pixel, in the outputimage array. In some variations of the present invention, K=4. In othervariations of the present invention, K=8.

According to further teachings of the present invention, there isprovided a computerized image acquisition system. The system includes afirst image sensor array having defective pixels, a second image sensorarray having defective pixels, and an image fusion module. The firstimage sensor array and the second image sensor array have substantiallythe same FOV and are aligned to view substantially the same scene. Foreach of the defective pixels of the first image sensor array, the imagefusion module selects the respective pixel from the second image sensorarray to be an output pixel of an output image array. For each of thedefective pixels of the second image sensor array, the image fusionmodule selects the respective pixel from the first image sensor array tobe an output pixel of the output image array. For each valid pixel inthe first image sensor array having a respective valid pixel in thesecond image sensor array, the image fusion module selects either of therespective valid pixels to be an output pixel of the output image array.

Preferably, the first defective image sensor array and the seconddefective image sensor array have no overlapping defective pixels.

In variations of the present invention, if the first defective imagesensor array and the second defective image sensor array haveoverlapping defective pixels, then for each of the overlapping defectivepixels, the image fusion module sets the value of a corresponding finaloutput pixel in the output image array to be the average of the Kimmediately adjacent neighboring pixels of the overlapping defectivepixel, in the output image array. In some variations of the presentinvention, K=4. In other variations of the present invention, K=8.

In variations of the present invention, if the first defective imagesensor array and the second defective image sensor array haveoverlapping defective pixels that have partial light energy sensitivity,a weighted average of the partially defective pixels is computed. Theweights are directly proportional to the partial light energysensitivity of each of the partially defective pixels. The computedweighted average is then assigned to the corresponding output pixel.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will become fully understood from the detaileddescription given herein below and the accompanying drawings, which aregiven by way of illustration and example only and thus not limitative ofthe present invention, and wherein:

FIG. 1 is a block diagram illustration of a camera system, according toembodiments of the present invention, built from two defective imagesensors;

FIG. 2 is a block diagram illustration of a camera system, according tovariations of the present invention;

FIG. 3 illustrates examples of a defective pixel having immediatelyadjacent valid pixels; and

FIG. 4 illustrates examples beam splitter configuration for camerasystems according to the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The present invention now will be described more fully hereinafter withreference to the accompanying drawings, in which preferred embodimentsof the invention are shown. This invention may, however, be embodied inmany different forms and should not be construed as limited to theembodiments set forth herein; rather, these embodiments are provided, sothat this disclosure will be thorough and complete, and will fullyconvey the scope of the invention to those skilled in the art.

Unless otherwise defined, all technical and scientific terms used hereinhave the same meaning as commonly understood by one of ordinary skill inthe art to which this invention belongs. The methods and examplesprovided herein are only illustrative and not intended to be limiting.

By way of introduction, a principal intention of the present inventionincludes providing a method for producing an imaging system having twoor more defective image sensors, yielding a single logical valid imagesensor.

Reference is made to FIG. 1, which is a block diagram illustration ofexemplary imaging system 100, according to embodiments of the presentinvention. Imaging system 100 includes two defective image acquisitiondevices 110 a and 110 b, each of which includes respective an imagesensor array, 130 a and 130 b, and an image fusion module 140 whereinthe methodology of image fusion module 140 yields a single output imageframe 150. Both image acquisition devices 110 have substantially thesame FOV and pointing substantially to the same distal object 20. Imagefusion module 140 selects valid pixels from either image sensors 130 aand 130 b to yield a single output image frame 150.

It should be noted that the manufacturing method of the presentinvention, substantially increases the image sensors production, forexample, the yield of IR image sensors may increase to over 90%.

Preferably, image sensor arrays 130 a and 130 b are selected such thatthere are no respective pairs of pixels, where both pixels aredefective.

The methodology of image fusion module 140 may be embodied in variousmethods. In a first embodiment, the methodology of image fusion module140 includes the following steps:

-   -   a) selecting image sensor 130 a as the primary image sensor and        image sensor 130 b as the secondary image sensor; and    -   b) for each pair of respective pixels, performs the following        steps:        -   i. if the pixel of the primary image sensor is valid,            setting the value of the corresponding output pixel in image            frame 150 to be the value of the pixel of the primary image            sensor; else        -   ii. setting the value of the corresponding output pixel in            image frame 150 to be the value of the pixel of the            secondary image sensor.

In a second embodiment, the methodology of image fusion module 140includes the following steps:

-   -   a) selecting image sensor 130 b as the primary image sensor and        image sensor 130 a as the secondary image sensor; and    -   b) for each pair of respective pixels, performs the following        steps:        -   i. if the pixel of the primary image sensor is valid,            setting the value of the corresponding output pixel in image            frame 150 to be the value of the pixel of the primary image            sensor; else        -   ii. setting the value of the corresponding output pixel in            image frame 150 to be the value of the pixel of the            secondary image sensor.

Reference is made to FIG. 2, which is a block diagram illustration ofexemplary imaging system 200, according to variations of the presentinvention. As in system 100, imaging system 200 includes two defectiveimage acquisition devices 110 a and 110 b, each of which includesrespective an image sensor array, 130 a and 130 b. Both imageacquisition devices 110 have substantially the same FOV and pointingsubstantially to the same distal object 20. Imaging system 200 furtherincludes an image fusion module 140 a which fusion module selects validpixels from either image sensors 130 a and 130 b to yield a singleoutput image frame 150 a, an image fusion module 140 b which fusionmodule selects valid pixels from either image sensors 130 a and 130 b toyield a single output image frame 150 b, an averaging module 240, whichaveraging module averages image frames 150 a and 150 b to yield a singleoutput image frame 250.

In a third embodiment, the methodology of image fusion modules 140 a,140 b and averaging module 240 includes the following steps:

-   -   a) performing the fusion method as in the first embodiment,        thereby creating an output image frame 150 a;    -   b) performing the fusion method as in the second embodiment,        thereby creating an output image frame 150 b; and    -   c) averaging each pair of pixels from image frames 150 a and 150        b whereby setting the value of a corresponding final output        pixel in image frame 250.

In variations of the present invention, image sensor arrays 130 a and130 b are selected such that there are a limited number of respectivepairs of pixels, where both pixels are defective. Reference is also madeto FIG. 3, which illustrates examples of a defective pixel 134 havingimmediately adjacent valid pixels 132. In such cases, at least one ofimage sensor arrays 130 a and 130 b are selected such that the mutualdefective pixels 134 have no immediately adjacent defective pixel 134.For the purpose of a clear description, with no limitation, image sensorarrays 130 a is taken as the image sensor array that has no immediatelyadjacent defective pixels 134. In such variations of the presentinvention, for each pair of mutual defective pixels 134, the value of acorresponding final output pixel in image frame 250 is set to be theaverage of the K immediately adjacent neighboring pixels 132 of thedefective pixel 134, in image sensor arrays 130 a. FIG. 3 illustratestwo examples: in one example K=4 and in the other, K=8.

In other variations of the present invention, image sensor arrays 130 aand 130 b are selected such that there are a limited number ofrespective pairs of pixels, where both pixels are partially defective.The output pixel is proportionally average from the partially defectivepixels. For example, pixel P_(i)a senses 60% of the arriving energy andpixel P_(i)b senses 75% of the arriving energy. In such a case theoutput pixel P_(i)out is averaged as follow:

P _(i)out=(P _(i) a*60+P _(i) b*75)/130.

Reference is also made to FIG. 4, which illustrates examples beamsplitter configuration for camera systems (100, 200) according to thepresent invention. In such variations, image acquisition devices 110 aand 110 b share a single front lens 170 and the incoming light is splitby beam splitter 180 into two beams, where a first beam is directedtowards image sensor arrays 130 a and the second beam is directedtowards image sensor arrays 130 a.

The invention being thus described in terms of embodiments and examples,it will be obvious that the same may be varied in many ways. Suchvariations are not to be regarded as a departure from the spirit andscope of the invention, and all such modifications as would be obviousto one skilled in the art are intended to be included within the scopeof the claims.

1. A method of manufacturing an image sensor from two defective imagesensor arrays having identical structural design, each havingsubstantially the same field of view (FOV) and aligned to viewsubstantially the same scene, the method comprising the steps of: a)providing a first defective image sensor array, having known defectivepixels; b) providing a second defective image sensor array, having knowndefective pixels; and c) fusing said first image sensor array and saidsecond image sensor array into a single output image array, wherein foreach of said defective pixels of said first image sensor array therespective pixel from said second image sensor array is selected to bean output pixel of said output image array; wherein for each of saiddefective pixels of said second image sensor array the respective pixelfrom said first image sensor array is selected to be an output pixel ofsaid output image array; and wherein for each valid pixel in said firstimage sensor array having a respective valid pixel in said second imagesensor array, either of said respective valid pixels is selected to bean output pixel of said output image array.
 2. The method as in claim 1,wherein said first defective image sensor array and said seconddefective image sensor array have no overlapping defective pixels. 3.The method as in claim 1, wherein said first defective image sensorarray and said second defective image sensor array have overlappingdefective pixels, and wherein the method further comprises the step of:d) for each of said overlapping defective pixels, setting the value of acorresponding final output pixel in said output image array to be theaverage of the K immediately adjacent neighboring pixels of saidoverlapping defective pixel, in said output image array.
 4. The methodas in claim 3, wherein K=4.
 5. The method as in claim 3, wherein K=8. 6.A computerized image acquisition system comprising: a) a first imagesensor array having defective pixels; b) a second image sensor arrayhaving defective pixels; and c) an image fusion module, wherein saidfirst image sensor array and said second image sensor array havesubstantially the same FOV and are aligned to view substantially thesame scene; wherein for each of said defective pixels of said firstimage sensor array, said image fusion module selects the respectivepixel from said second image sensor array to be a corresponding outputpixel of an output image array; wherein for each of said defectivepixels of said second image sensor array, said image fusion moduleselects the respective pixel from said first image sensor array to be acorresponding output pixel of said output image array; and wherein foreach valid pixel in said first image sensor array having a respectivevalid pixel in said second image sensor array, said image fusion moduleaverages said valid pixel in said first image and said valid pixel insaid second image and assigns said average to a corresponding outputpixel of said output image array.
 7. The system as in claim 6, whereinsaid first defective image sensor array and said second defective imagesensor array have no overlapping defective pixels.
 8. The system as inclaim 6, wherein said first defective image sensor array and said seconddefective image sensor array have overlapping defective pixels, andwherein said image fusion module, for each of said overlapping defectivepixels, sets the value of a corresponding final output pixel in saidoutput image array to be the average of the K immediately adjacentneighboring pixels of said overlapping defective pixel, in said outputimage array.
 9. The system as in claim 8, wherein K=4.
 10. The system asin claim 8, wherein K=8.
 11. The system as in claim 8, wherein saiddefective pixels are partially defective pixels, having partial lightenergy sensitivity, and wherein said image fusion module computes aweighted average of said partially defective pixels, wherein said weightis directly proportional to said partial light energy sensitivity ofeach of said partially defective pixels; and assigns said weightedaverage to said output pixel.